Project Summary (Project 2) The overall goals of Project 2 are to study the origins and later development of human oligodendrocyte precursor cells (OPCs) in fetal human cortex during 20-40 weeks gestation age (GA). We will study processes of OPC proliferation, the nature of their migratory behavior and differentiation in situ the relationship to the outer subventricular zone (oSVZ); a germinal zone present in 3rd trimester human brain that may account for significant gliogenesis. Specific aims include a detailed exploration of OPC lineage ontogeny in human cortex, based on anatomical and immunolabeling marker analysis of both acutely harvested cortical tissue and specimens from the Core B tissue bank. We will perform dynamic imaging of proliferation in fetal slice cultures to test our hypothesis that a transit amplifying OPC undergoes multiple rounds of symmetric divisions to provide the very large number of OL cells needed to myelinate axons in human cortex. We also plan to develop the ferret as an animal model of OL development with the expectation that oligodendrogenesis will mimic that of the developing human brain but on a compressed timescale. We will use the fetal gyrencephalic ferret cortex that can be manipulated experimentally; so that the combined study of human and ferret will provide a more complete understanding of OL development and maturation. Finally, We will use both human and ferret cortex in complementary fashion to determine if the developing ferret cortex can be used to model the effects of hypoxia in the preterm human. We will test the hypothesis that low O2 tension promotes fetal oligodendrocyte proliferation and inhibits differentiation, while high O2 inhibits oligodendrocyte proliferation and promotes differentiation. White matter injury is associated with cerebral palsy in premature infants, but the specific effects of O2 tension on the cell lineage leading to the production of a myelinating oligodendrocyte has not been well defined in animals or humans. The results may eventually help us better understand the causes of and guide the clinical management for premature newborn infants at risk for these disorders.